1. Field of the Invention
The present invention relates to an optical switch for use in optical fiber communication and optical network technology, and particularly to an optical switch that can precisely locate a movable optical component to preselected positions for realizing optical paths switching.
2. Description of Related Art
Optical signals are commonly transmitted in optical fibers, which provide efficient light channels through which optical signals can pass. Recently, optical fibers have been used in various fields, including telecommunications, where light passing through an optical fiber is used to convey either digital or analog information. Efficient switching of optical signals between individual fibers is necessary in most optical processing systems or networks to achieve the desired routing of the signals.
In optical fiber systems, various mechanisms have been previously developed for switching optical signals between fiber cables. Among these previously developed mechanisms, one important category is mechanical optical switches.
Mechanically operated optical switches come in two different designs: in one design, the optical components move, and in the other design, the fibers move. Factors for assessing the capability of an optical switch include low insertion loss (<1 dB), good isolation performance (>50 dB) and bandwidth capacity compatible with the fiber network the switch is supporting.
In moving optical component switches, a driving mechanism drives one or more optical components to move between different positions to effect the switching operation. The driving mechanism may be a motor or a solenoid with no self-latching mechanism, which needs an attached latching mechanism to locate the optical component in the different positions. In general, the attached mechanism is large in size. As shown in FIG. 10, U.S. Pat. No. 5,742,712 describes a mechanical optical switch 910 having a relay 912. The relay 912 includes an arm 940, which supports a mirror 920. In response to electrical signals supplied to the relay 912, the arm 940 of the relay 912 moves the mirror 920 between a first position 944 and a second position 946. The travel of the arm 940 is limited by stops 948, which determine the first and second positions of the mirror 920.
In this mechanical optical switch 910, the stops 948 are opposite a middle part of the arm 940. The weight of the mirror 920 bends the arm 940 over time, which results in misalignment of the mirror 920 and connected fibers 990.
For the above reasons, an improved optical switch is desired. In particular, an optical switch is desired which has high optical efficiency and which can precisely position the switching element in the different switching states.